Improvement in preventing the deviation of ships  compasses



. zsheets-sheet 1. J. W. GIRDLESTONE.

Ships Compass. No. 108,585. Patented 001;. 25,1870.

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J. W. GLIRDLESTDNE. Shps Gompass. No 108,585. Patented I001:. 25, l1870.

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JOHN WARD GIRDLESTONE, N0. 37 NOR-FOLK STREET, STR-AND, ENGLAND.

Letters Patent No. 108,585, dated October 25, 1870.

IMPROVEMENT INPREVENTING THE DEVlATiON OF vSHIPS COMPASSES.

YThe Schedule referred to in these Letters Patent and making part of the same 'said JOHN WARD GmDLEsToNE, do hereby declare the nature of the said invention, and in what manner the sameis to be performed, to be particularly described and ascertained in and by the following statcment'thereof; that is to say- This invention relates to' a novel method of correcting and preventing compass deviations in iron, steel, or composite ships or vessels, by polarizing, on the regulated system hereinafter specified, such parts of the ships or vessels as may be requisite, and by the simultaneous employment, in some cases, of soft` iron.4

With a view to explaining the principle of' my invention, I will notice briefly the cause and nature of compass deviations.

It is generally understood'- `First, that the deviations of the compass from the magnetic meridian are due to the .magnetismot' the ship.

Second, that the deviations, observable by the aid of a horizontal needle when the ship is on au even keel; consist of two principal parts, termed semicircular? and quindi-auml, with the addition, in some eases, of a small part., termed const-ant.

Third, that the semicircnlar*deviation consists of two parts, one arising from vertical induction, (which, in .a well-placed compass, is,in general, but small,) the other arising from the permanent magnetism of the ship, and varying in character with the position of the ship when on the bnilding-slip.

Third, that the scmicircular deviation is caused by a force acting in a particular direction -in the ship, which' force may, in general, be conveniently resolved into two forces, one acting in the forc-and-aft line of the ship, and the other act-ing athwvart ship.

Fourth, that the .quadrantal deviation is caused by horizontal induction.

Fifth, that the lconstant deviation arises mainly from two causes, namely, a, horizontal induction in soft iron nnsymmetricaljy arranged, and, l, instrumental error. f

Sixth, that, besid,esI the deviations observable by the aid of a horizontal needle when the ship is on an even keel, there are likewise the errors that arise when the ship heels over, termed, respectively, semicircular heeling, quadrantal vliceling, and constant heeling. v

Seventh, that the semicircular heeling error is caused, as to the greater part, by the vertical force of the ship, (i. e., by vertical permanent magnetism, and by vertical induction iu vertical iron,) and, as to the lesser part, by verticalinduction in transverse llOll.

Eighth, that the quadrantal-heeling error and the constant-heeling error are, (in the case of a well-placedl compass,) in general, so small as to be disregarded with safety in the navigation of a ship.

According to my invention, I correct the semicir l cular deviation, and, in some cases, the semicircnlarheeling error, by polarizing (either in whole or in part,

as may be advisable) either one or more of the deckbeams, or the hull, or the stringers, or the ribs, rthe stern-post, or any or each of these p arts of the ship or vessel, or any other parts thereof, as may be requisite or advisable also, I correct (whenadvisable) the quadrantal deviation, and, in part, both the semicir cular deviation and the heeling error, by means of soft iron.

It may be well to remark that, although it may, in

some cases, be convenient to polarize, (either in whole or in part,.) for the purposes hereinbefore named, any, each, or either of the above referred to parts of the ship or vessel yet, as a rule, it is more convenient to polarize, for the same purposes, deck-beams only. I, therefore, hereinafter more particularly 'specify my mode of proceeding when polarizing deck-beams only,

.and bythe aidot' this specification any competent person will be readily enabled, in any ease, (if requisite or -advisable,) to polarize, in accordance with my invention, any, each, or either of theother above referred to parts ot' the ship or vessel.

With a view to explaining the practical. details of my invention, I will presently describe a pmcess (to which process, as a separate part of my invention, I make no claim,) whereby bars of hard iron or steel (including the deck-beams of a ship) may befconverted into magnets of two classes, which .may be conveniently termed simple and compound. y

, By a simple magnet I here mean, first, that which has two poles only, namely, either at or toward its ends, or ,'at points equidistant from its center, poles of opposite names; and, second, thatwhich (as re- -gards its practical effect ,on the ships compass) is equivalent-to rst, and 'has more than two poles, of which those situated nearest to and at either side ot' its center are of opposite names. l

By a compound magnet I here mean, first, that which has three poles only, namely, a central pole ,of one name, and, either at or toward its ends, or at. points equidistant from'its center, poles of the oppo-v site name; and, second, that which (as regards its practical effect ou the ships compass) is equivalent to iirst, has more than three poles, has no central pole,

and whose poles situated nearest to and at either side of its center, are equidistaut therefrom, and are ofthe same name.

Simple magnets may, for the sake of convenience, be divided into two classes: rst, those whose poles, situated nearest to and at the right-hand (orl starboard) side of 4their centers, are north; second, those whose similarly-situated poles are south.

Compound magnets may be likewise divided into two classes: first, those whose central poles,or (in the case of magnets that have no central poles) whose poles situated nearest to and at either side of their centers, are north second, those whose similarly-sit uated poles are south.

Iwould have it understood that, when I employ the term center, I in tend by this term to indicate (in the case of a deck-beam of a ship) that part of the beam which would be intersccted by a line passing through the middle of the compass, and running along or parallel to the midship line of the vessel.

I will n ow describe a mode of producing what are, as a`rule, both the simplest and the ,most convenient forms of both simple and compound magnets, and by the aid of the following description any competent person will he readily enabled to produce, if needful,

- any other equivalent forms of these n'iagnets.

I rst describe a mode of net of the first class. t

Let the thin 'horizontal line, Figure l, represent thc bar proposed to be polarized. Ilace thereon, at or toward either of its ends, the horseshoe-magnet af, so that its poles may bc parallel to the longitudinal axis of the bar, its south pole' heilig turned toward the in- ?tendcd north pole of the bar. lhen p'ass the magnet :i: from cud to end ofthe bar, when at or toward that end of the bar toward which the south pole of the horseshoe-magnet was turned there will be a north pole, and at or toward the other end ofthe bar there will bc a south pole. By repeating this operation, and by regulating the strength of the horseshoe-inagnet, the strength of the bar-magnet thus produced may be regulated; and, if, from any cause, the requisite strength should be exceeded, then, by very carefully reversing the operation, the strength of the harmagnet may be reduced.

'A simple magnet of the second class may be produced by reversing the operation above described for the production of y a simple magnet of the iirst class.

Figure4 2 is drawn in illustration of a mode of pro ducing a simple magnet of the second class.

I next describe a mode of producing a compound magnet of the first class. y

Let the thick horizontal line, iig. 3, represent the bar proposed to be polarized. llace thereon, between the center (shown by th c intersection of two dotted lines) and one of the ends of the bar, and near either, to the end, or to the center ofthe bar, the horseshoemagnet zu, so that its poles'may be parallel to the longitudinal axis of the bar, its south pole being turned toward the intended central north .pole of the bar. 'lhen pass the magnet :u between the end and producing a simple magthe center of the bar. Next, remove the horseshoe-A magnet from the half 'of the fbar thus treated,.and placeit on the other half ofthe bar, so that its poles may be parallel to the longitudinal. axis, of the bar, its south pole being turned toward the intended central north pole of the bar. Then pass the magnet a: between the cud and the center o t' the bar, when at the centerof thc bar` therewill be a north pole and at or toward the ends thereof there will be south poles.

The strength of thebar-magnet thus produced may be regulated ou the same principle as that described with reference to the regulation of the strength of a simple magnet of the first class,

A compound magnet of the second class may he produced by reversing the operations above described, for the production of a compound magnet of the first class.

Figure 4 is drawn in illustration of a mode ol' producing a compound magnet of the second class I would have it understood that when hereinafter I employ either of the terms simple magnet of the iirst class, simple magnet of the second class, compound magnet of the first class, or compound magnet ofthe second class, I intend, under each of these terms to include any magnet that shall, when produced under the conditions hereinafter specified, and in accordance with the six rules hereinafter laid down, give a practical result equivalent tovthat which may be arrived at on producing,as above' directed, under the same conditions and in accordance with the same rules, the magnet ofthe same tcrtn.

When polarizing a bar of iron or` steel ora deckbeam of a ship, I usually employ either a permanent magnet or an electro-magnet, and I usually place/the ma guet with which I operate in contact with the bar; but, if from any cause I find this course either impracticable or inexpedient, I place the'magnet as near tothe bar as may be practicable or expedient, and proceed with the operation as it' the' magnet were in contact with the bar; I therefore, when polarizing a deck-beam of a. ship, either bring-the magnet with which I operate into contact with the beam, or I mark or chalk out on the deck, im-nxediately above the said deck-beam, the exact position of the beamr and pass the magnet along the line thus indicated, as if along the beam itself.

In the case of-a ship whose deck-beams are constructed of any material other than hard iron 'or steel, it may be found convenient, for the purpose of correcting and preventing compass deviations, to introduce beneath the deck, and 'near to the compass, two or more bars or beams of hard iron orsteel.

In reference to my diagrams or iignres numbered 5 Ato 54 inclusive, which figures are drawn in illustration of some convenient modes ofrcprrccting under dilercnt conditions referred to hereafter as leading and secondary, 4the deviations of any compass, I would remark that in each diagram or figure a circle represents the compass; and, furthcnthat in each diagram or figure each thin horizontal line represents a deck-beam of either iron or steel, which I convert into a simple magnet of the iirst or second class, and each thick horizontal line represents a deck-beam of either iron or steel, which I convert into a compound magnet ot' the first or second class, according as it may be necessary to effect the conversion, in order to correct the deviations of the compass, as and in the manner .hereinafter described.

The leading conditions under which my invention may be carried ont are the following:

First when the shi s'head is )laced successivel 7 p .l

` on two of the foul' cardinal points,-namely,at north or south and at east or west;

Second, when the shi .1 head is placed on one only of the four cardinal points; and

Third, when the ships head is placed on any bearingother than either of the four cardinal points.

In proceeding to carry ont my invention under the Erst leading condition above stated, I place the ships headin the first instance, by preference, cast 0r west, correct magnet-ic.

The vertical force of the ship causing the-greater part of the semicircnlar heeling error may be t-hcn observed by comparing, in a plane at right angles to the meridian, the times-of a given number ot vibrations of a dipping-needle onboard ship and ou shore, placing the dipping needle on hoard ship over the centre of a deck-beam in a position suitable for the ships compass, a mode of observation to which I make no claim, as forming a separate part of my invention also. Iin some cases correct, either iuwholc or in part, the semicircular heeliug crror by correctly proportoning the times of` the vibrations on vboard ship and ou shore through the application of Rules I and II, which rules, with the others below referred to, are hereinafter set forth; also, I correct that part of the semicircnlar deviation whichis caused by a force acting in thc fore-and -aft line of the. ship, through th;` application of Rules III and IV. I next place the ships head north o1` south, correct magnetic, and, through the application of R-ules V and VI, correct that part of' the semicircular deviation which is caused 'by a force acting athwart ship.

It, from any cause, the operations have to be com-- menced when the ships head is placed either north or south, correct magnetic, thc force causing the liceiing error may be observed by the aid of a dippingneedle, and, should the error be such as to n ced correct-ing, I place the compass over the center of a deck-beam, and through the application ot Rules V and VI, correct that part of the semicircnlar deviation, which is caused by a force acting athwart ship, reserving, as a rule, the correction ofthe hecling error until the ships head is placed east or west, correct magnetic, at which bearing, through the application of Rules III and IV, I likewise cor: rect that part of .the se'micircular deviation which is caused by a force acting in the fore-and-aft line of the ship.

In proceeding to carry out my invention underthe second leading condition above stated, -I place the ships head, by preference, east or west, correct magnetic; also, through the application ot' Rules I and II, I correct, either in whole o1' in` part, the semicircular heeling error as already directed; also, through the application of Rules III and IV, I correct that part ofthe semicircular deviation which is caused by a force acting in the fore-and-aft line ot' the ship.

lheforce, acting athwart ship, and causing the other part of the semicircular deviation, may be observed hy comparing the times of a given` number of vibrations of a horizontal needle on board ship and on shore,

(a mode of observation to which I make uo claim, as forming a separate part of my invention,) and I correct the deviation by correctly proportioning thc-times ci' the vibrations on board ship and on shore, and, when thc shipshead is east, and the time of the vibrations on board is too great, as compared with the time of the vibrations onshore, or when the ships head is west, and thc time of the vibrations'on board is too small as compared with the timeof the vibrations on shore, it is inferablc that, with thc ships head north, there would be an easterly deviation, and with the ships head south, there would bc a westerly deviation, and I then effect the correction through the application of Rule V; and when the ships head is east, and the time ot' the vibrations on board is too small as compared with the time of the vibrations on shore, or when the ships head is west, and the 4time of the vibrations on board is toogreat as compared with the time ot the vibrations on shore, it is inferable that, with the ships head north, there would be a westerly deviation, and that, with the sliips head south, there would be an easterly deviation and I then effect the correction through t-hc application of Rule VI.

If, from any canse, the operations have to be carried out when the ships head is placed either north or south, (correct magnetic,) I, in some cases, Ycorrect (either in whole or in part) theheeling error through the applicatiouof Rules I fand II, placing the c ompass, for this purpose, over the-center of adeck-beam; also, I correct, through thc application of Rules losses 3 which is caused by a force acting athwart ship.

I he force, acting in the fore-and-aft line ofthe ship,

given number of vibrations of a horizontal ncedle'on board ship and on shore, and I correct the deviation by correctly proportioningthe times of the vibrations on board ship and on shore, and, when the ships head is north, and the time of the vibrations on boa-rd is too small as compared with the time of the vibrations on shore, or when the ships head is south, andthe time of vibrations on board is too great as compared'wit-h the time of the vibrations on shore, it is infer-able that, with the ships head east, there would bc an easterly deviation, and that, with the ships head west, there would be a westerly deviation; andI 'then elect the correction through the applicationof Rule III; and, when the ships head is north, and the ltime of the vibrations on board istoo great as compared with the time ofthe vibrations on shore, or when the ships board is too small as com pared'with the time of the head cast there would bela westerly deviation, and that, with the ships head west, there would be an easterly deviation; and I then effect the correction through the application of Rule IV. 1

In proceeding to carry out my invention under the; third leading condition, above stated, I correct, where desirable, thc heeling crror (either in whole orin part) bythe aid ot' a dipph'ig-necdle, and through the ap.`3

late, or otherwise ascertain what would be, c, the di n rectly observable deviation, and, b, the. horizontal force (at the bearing at which the vessel lies during the operations umler the four circumstances follow-'-v ing, namely:

First, if the semicircular deviation were in no partcorrected v Second, if that pa-rt only of 'the semicircular devi-l ation cau/Sed by a force acting in the fore-and-aft line of the ship were corrected;

Third, if that part only of the semicircular deviation caused by a force acting athwart ship were corrooted; and

Fourth, if the entire semicircuhir .deviation were corrected.

Also, I either correct that part ot' the seinicircular deviation caused by a force acting in the fore-and-aft line of the ship, by reducing or increasing (as may be requisite) both the directly-observable deviation and the horizontal force, until they eqiial the deviation andthe force previously ascertained to exist' when this part of the scmicircular deviation shall have been corrected, and when it is inferable that, with the ships head cast therewould'be lau easterly deviation, and that with the ships head west, there would bea westerly deviation, I effect the correction through the application of Rule III; and when it is inferable that with the ships head cast there would be a westerly deviation, and that with the ships head westthere through the application of Rule IV; or I correct that part of the se'mioircnlar deviation caused by a forcc'actiug athwart ship, by reducing or increasing (as may be requisite) bot-h the directly-observable de- ,.viation and the horizontal foro e,.until they equal the deviation and the forcepreviously ascertained to exist when this part oi' the semicircular deviation shall have been corrected, and when it i's inferable that with the ships head north there would be an easterly 4dewould he n. westerly deviation, I effect the correction and causing the other part of the semicircular devia.-Y tion, maybe observed by comparing the times of a head is south, and the time of the vibrations on V and VI, that part of the semicircular deviation I vibrations onshore, it is inferable that withthe ships plication of Rules I and II; also, I observe, calcu-.

would be an easterly'deviation, .I effect the correction viat--on, and that with the ships head south there through the application of Rule Y; and when it is inferable that with the ships head north there would be a westerly deviation, and that with the. ships head south there would be an easterly deviation, I effect the correction through the application of Rule VI; also, I correct the remaining part of the scmieirciilar deviation by reducing,r or increasing, as may be-requisite, (through the application, as inference may direct, ct' RulesIII and IV, if the deviation to bc corrected be that caused by a force acting in the fore-- and-aft line ofthe ship, and through the application,

as4 inference may direct, of Rules V and VI, if thc deviation to bc corrected be that caused by a force acting athwart ship,) both the remainder ot' the directly-observable deviation and the horizontal force, until they equal thc deviation and theforce previously ascertained to exist when the entireY sen'iicircular ldeviation shall have been corrected.

Before giving my six rules, to which .I have made reference, I would remark- First, that of my fifty-four diagrams of figures, those only that are numbered 5 to 39 inclusive, may be employed, in conjunction with Rules I and II, while those numbered 5 to 54 inclusive, may be employed in conjunction with Rules III, IV, V, and VI.

Second, that my six rules are so d 'awn np as to be serviceable, if needful, apart from myiignres.

Rules.

I. \Vhen the time of the vibrations on board ship is too small, as compared with the time of the vibrations on shore, convert the deck-beam beneath the compass into a compound magnet of the first class.

II. \Vhen the time of the vibrations onboard ship is too great, as compared with the time of the vibrations on shore, convert the deck-beam beneath the compass into a compound magnet ofthe second class.

III. When the ships head is east,.and the deviation east, or when the ships head is west, and the deviation west, convert either, a, one or more deckbeams, lying, either wholly or in part, within a radius of about twenty/feet of the compass, -or b., every deck-beam represented on any figure by a thick line, into a compound magnet of the iirst class, if 'ahead "of the compass, and in o a compound magnet of the second class ifastern of the compass.

1V. When the ships head is cast, and tac deviation west, or when the ships head is west, and the' deviation east, convert either, a, one or moredeekbeams, lying, either wholly or in Apart, within a ra- `\dins ot' about twenty feet o t' the compass, or, 1),' every leck-beam represented on any figure by a thick line, itc a compound magnet of the. second class, it' ahead "the compass, and into a compound magnet of the ii "t class, ifastern ofthe compass.

\Vheu the ships head is north, and the devia- .etici east, or when the ships head is south, and the .deviation west, convert either, a, one or more deckbeams, lying, either wholly or in part, within a -ra- 4,dius. of about twenty feet lof the compass, whether ahead or astern thereof, or, except where the. heeling` error is, or is to be corrected, beneath the same, or, Il, every deck represented on any figure by a thin lille, whether ahead, beneath, or astern of thecoinpass,'into a simple magnet ofthe iirst class.

VI. \Vhen the ships headis north, and the deviation west, or when the ships head is south, and the deviation east, convert either, a, one or more deckbeams, lying, either wholly or in part,-within a radius of about twenty feet of the compass, whether ahead or-astern thereof, or, .except where the heeling error is, or is to be corrected,beueath the same,

u or, b, every Hdeck-beam represented on any ligure by "a thin line, whether ahead, beneath, oi-'"astern of the compass, into a simple magnet, of the second part.

The secondary conditions under which my inven-' tion may have Eto be carried out will be fully understood, and my invention will be readily adapted to them by any competent person conversant with 4the subject, and acquainted with the details of this specitication.

It will be perceived that the deck-beams shown on my diagrams varyin number, aud'that the compass is represented in various posit-ions with regard to these beams.

In some cases, owing Vin part tothe number of available deck-bean'is being limited, and in part to their position relative to the compass being, from dierent circumstances, immntably fixed, there will be found practically little or no room for the exercise ot' choice as to which', if any,`of the different arrangements herein referred to, it may be best to adopt, and in these cases, those beams that are accessible to the opera-tor must be dealt with as experimic'e--niay direct; and in any casc it will be well to bear-in mind the two rules following, namely:

First, that it is of Vmore importance to have a considerable number of deck-beams on whieh to operate when the deviations ot' a compass are great than when they are small; and

Second, thataccording as ,that part of the semicircular deviation caused by a force acting athwart ship is great or small, in comparison with Vthat part caused by a force act-ing in the fore-and-aft line of the ship, the beams available for conversion into simple magnets should, as compared with thosel available for conversion into compound magnets have, (l), the advantage, or (2), the disadvantage either, a, in ninnber, or, b, in proximity to the compass.

1t', on preliminary observation, I tind the deck-beam or beams, which I purpose polarizing, with a view to the correction of that part ot` Ythe semicircular deviation which I correct second, so strongly magnetized as to affect the compass; or it', in cases when I correct the heeling error, after the eorrectionot` either or cach part of' the semicircular deviation has been effeeted,.I find the deck-beam, which I purpose polarizing, with a view to the correction of' the hecling error so strongly magnetized as to ali'ect the coinpass, I, in some cases, before proceeding to correct the'deviations of the compass, so far temporarily depolarize `these said beams, adopting the same principle as that involved in the depolarization of a polarized bar, as to destroy 'temporarily their effect on the compass.

I would here remark that, after carrying out my invention under either of the three leading conditions above stated, the ships head may, when advisable, be placed on the bearing, or on cit-her of, or on each of the bearings on which it may have been previously placed, or it may be placed on any fresh bearing or bearings, and the operations in the lirst instance carried out may be cheeked; and by the aid of this specification any competent person will be readily enabled, it' requisite, to carry on't my invention, either in whole or in part, as may be requisite, at the fresh bearing or bearings on which the ships head may be placed.

A vertical column or pillar of soft iron may, when advisable, be employed for the purpose of correcting that part of the semicircular deviation which is caused by vertical induction, andsoft-iron rods, cylinders, or chains may, when advisable, be employed for the purpose of correcting, a., the quadrantal ldeviation, and

vb, `the semicircular heeling error. But I make no claim touse either of such vertical columns or pillars of soft iron, or ot' such soft iron-rods, cylinders or chains, as forming :L separate part of my invention.

Having now described my' system of correcting and preventing,r compass deviations, I would have it understood that I claim as my' invention- 1. The process of treating iron, steel, or composite ships or vessels to correct; and prevent compass cleriations by polarizing onthe regulated system herelosses inV specified, such parts of the ships or vessels as may be requisite.

2. The employment of' soft: iron, in conjunction with my system of polarization, for -the purpose of correcting compass deviations, i,

. JOHN lVAR-D GIRDLESTONE.

Witnesses:

G. F. WARREN, No. 17 Gracec'vm'ch Street, THos. BROWN. London. I 

